1. Field of the Invention
This invention relates to microlithography, and more specifically relates to maskless patterning of high-resolution microelectronics features on large-area curved substrates.
2. Description of Related Art
Microelectronics patterning on large substrates, and microelectronics patterning on curved substrates, and microelectronics patterning using maskless techniques, are all the subjects of patents and products of the Anvik Corporation. Large area lithography techniques developed by Anvik Corporation generally use a mask and substrate mounted on the same high-precision positioning stage, combined with imaging through a folded projection system and exposure with partially overlapping, complementary-illumination scans, so that the patterning exposure is seamless over the large area. See, for example, U.S. Pat. No. 5,285,236, issued Feb. 8, 1994, Ser. No. 07/954,662, filed Sep. 30, 1992, LARGE-AREA, HIGH-THROUGHPUT, HIGH-RESOLUTION PROJECTION IMAGING SYSTEM, K. Jain.
Maskless lithography techniques developed by Anvik Corporation generally use a programmable spatial light modulator array to produce the pattern, instead of using a mask. See, for example, U.S. Pat. No. 6,312,134, issued Nov. 6, 2001, SEAMLESS, MASKLESS LITHOGRAPHY SYSTEM USING SPATIAL LIGHT MODULATOR ARRAY, Ser. No. 09/230,438, filed Jul. 25, 1996, K. Jain, T. J. Dunn and J. M. Hoffman.
Lithography techniques developed by Anvik Corporation for patterning on curved substrates generally require vertical motion of the mask and/or substrate so as to maintain the light beam path length constant between the mask and substrate. See, for example, U.S. Pat. No. 6,304,316, issued Oct. 16, 2001, K. Jain, N. O. Farmiga and T. J. Dunn, MICROLITHOGRAPHY SYSTEM FOR HIGH-RESOLUTION LARGE-AREA PATTERNING ON CURVED SURFACES, Ser. No. 09/176,920, filed Oct. 22, 1998.
No lithography technology for maskless patterning of high-resolution features on large curved surfaces has been reported to-date. The reason may possibly be that the large-area lithography techniques, the maskless lithography techniques, and the curved-substrate lithography techniques are all difficult to design and build, and because there is no simple way to combine the techniques while maintaining proper optical conjugates and other imaging characteristics. This invention presents solutions to the problem of maskless patterning on a large-area curved substrate with high throughput.
It is the object of the invention to provide a novel system of maskless patterning of a large curved microelectronics substrate at high resolution with high throughputs.
Another object of the invention is to maintain high resolution of image, even though substrate curvature may tend to vary the light beam path length between the spatial light modulator array and the substrate, creating optical variations which can affect feature quality.
A feature of the invention is the use of a 2-D spatial light modulator array which is movable in both translation and tilt, and a movable projection lens system to keep the total light beam length constant while maintaining focus.
Another feature of the invention is the use of a segmented spatial light modulator array array with each segment on its own axial positioner, to match the averaged spatial light modulator array surface profile with the local curvature of the substrate.
An advantage of the invention is that the system can be conformed to known deliberate curvature of the substrate and also can accommodate to random substrate anomalies of curvature, including edges.
Another advantage of the invention is that the composite system is capable of high resolution in very small production runs, even with randomly curved substrates.
Still another advantage of the invention is that maskless patterning on curved surfaces may be accomplished by additional elements mounted outside the optical path, using optical elements present in the optical path of a common systemxe2x80x94thus being subject to retrofit or economical new manufacture.
Other objects, features and advantages of the invention will be apparent from the following written description, claims, abstract and the annexed drawings.